Any of the cultivated forms of the annual legume Vigna unguiculata. The plants are believed to be native to India and the Middle East but in early times were cultivated in China. The compound leaves have three leaflets. The white, purple, or pale-yellow flowers usually grow in twos or threes at the ends of long stalks. The pods are long and cylindrical. In the southern U.S. the cowpea is grown extensively as a hay crop, as a cover or green-manure crop, or for the edible beans.
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Cowpeas are one of the most important food legume crops in the semi-arid tropics covering Asia, Africa, southern Europe and Central and South America. A drought tolerant and warm weather crop, cowpeas are well-adapted to the drier regions of the tropics, where other food legumes do not perform well. It also has the useful ability to fix atmospheric nitrogen through its root nodules, and it grows well in poor soils with more than 85% sand and with less than 0.2% organic matter and low levels of phosphorus. In addition, it is shade tolerant, and therefore, compatible as an intercrop with maize, millet, sorghum, sugarcane, and cotton. This makes cowpea an important component of traditional intercropping systems, especially in the complex and elegant subsistence farming systems of the dry savannas in sub-Saharan Africa. Research in Ghana found that selecting early generations of cowpea crops to increase yield is not an effective strategy. Francis Padi from the Savannah Agricultural Research Institute in Tamale, Ghana, writing in Crop Science, suggests other methods such as bulk breeding are more efficient in developing high-yield varieties.
Southern peas are a common food item in the southern United States, where they are sometimes called crowder peas. They are so named because they appear to be crowded into their pods. The crowding causes them to have a squarish shape rather than round.
According to the USDA food database, cowpeas have the highest percentage of calories from protein among vegetarian foods.